A new type of congenital disorders of glycosylation (CDG-Ii) provides new insights into the early steps of dolichol-linked oligosaccharide biosynthesis

Thiel, Christian and Schwarz, Markus and Peng, Jianhe and Grzmil, Michal and Hasilik, Martin and Braulke, Thomas and Kohlschuetter, Alfried and von Figura, Kurt and Lehle, Ludwig and Koerner, Christian (2003) A new type of congenital disorders of glycosylation (CDG-Ii) provides new insights into the early steps of dolichol-linked oligosaccharide biosynthesis. JOURNAL OF BIOLOGICAL CHEMISTRY, 278 (25). pp. 22498-22505. ISSN 0021-9258, 1083-351X

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Abstract

Deficiency of GDP- Man: Man(1)GlcNAc(2)- PP- dolichol mannosyltransferase ( hALG2), is the cause of a new type of congenital disorders of glycosylation ( CDG) designated CDG- Ii. The patient presented normal at birth but developed in the 1st year of life a multisystemic disorder with mental retardation, seizures, coloboma of the iris, hypomyelination, hepatomegaly, and coagulation abnormalities. An accumulation of Man1GlcNAc2- PP- dolichol and Man(2)GlcNAc(2)- PP- dolichol was observed in skin fibroblasts of the patient. Incubation of patient fibroblast extracts with Man1GlcNAc2- PP- dolichol and GDP- mannose revealed a severely reduced activity of the mannosyltransferase elongating Man1GlcNAc2- PP dolichol. Because the Saccharomyces cerevisiae mutant alg2- 1 was known to accumulate the same shortened dolichol- linked oligosaccharides as the patient, the yeast ALG2 sequence was used to identify the human ortholog. Genetic analysis revealed that the patient was heterozygous for a single nucleotide deletion and a single nucleotide substitution in the human ortholog of yeast ALG2. Expression of wild type but not of mutant hALG2 cDNA restored the mannosyltransferase activity and the biosynthesis of dolichol-linked oligosaccharides both in patient fibroblasts and in the alg2- 1 yeast cells. hALG2 was shown to act as an alpha1,3- mannosyltransferase. The resulting Manalpha1,3-ManGlcNAc(2)- PP dolichol is further elongated by a yet unknown alpha 1,6- mannosyltransferase.

Item Type: Article
Uncontrolled Keywords: GDP-FUCOSE TRANSPORTER; SACCHAROMYCES-CEREVISIAE; OLIGOSACCHARYLTRANSFERASE COMPLEX; PHOSPHOMANNOMUTASE DEFICIENCY; PROTEIN GLYCOSYLATION; YEAST; GENE; MUTATIONS; MANNOSYLTRANSFERASE; DISEASE;
Subjects: 500 Science > 580 Botanical sciences
Divisions: Biology, Preclinical Medicine > Institut für Pflanzenwissenschaften > Lehrstuhl für Zellbiologie und Pflanzenphysiologie (Prof. Dr. Klaus Grasser)
Depositing User: Dr. Gernot Deinzer
Date Deposited: 11 Aug 2021 04:48
Last Modified: 11 Aug 2021 04:48
URI: https://pred.uni-regensburg.de/id/eprint/38893

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